This invention relates to an induction system for a fuel-injected engine and more particularly to a control and the physical relationship of the components of such an induction system and engine.
It has been recognized that the performance of an engine can be significantly improved if the volume of the induction passage between the throttle valve and the intake port is correctly proportioned relative to the total volume displaced in the combustion chamber including the clearance volume. This latter volume is referred to as the "exhaust gas volume per cylinder". If this ratio is kept quite small, for example in the range of 0.15 to 0.45, performance can be significantly improved. Such arrangements are disclosed in the co-pending applications both entitled "Engine Having Combustion Control System", Serial Nos. 09/016199 and 09/025064, filed Jan. 30, 1998 and Feb. 1, 1998, respectively, and assigned to the assignee hereof. With this type of arrangement, the resulting construction places the throttle valve quite close to the intake port. This gives rise to certain problems including some of those mentioned and overcome in the aforenoted co-pending applications. However, there are still other problems that exist.
Because of the close location of the throttle valve to the intake port, when intake air volume is increased rapidly, the air fuel ratio may be disturbed and cause poor firing and combustion in the combustion chamber. This is partially a result of the fact that the fuel flow amount does not increase as rapidly as the air flow amount due to its relatively greater inertia. This problem is what causes carbureted engines to utilize accelerating pumps. Such a concept is somewhat more difficult to embody in a fuel-injected engine.
This running condition frequently happens when racing the engine or what is called "blipping the throttle" occurs when operating under low or no-load conditions in order to clear the engine and keep it running smoothly.
It is, therefore, a principal object of this invention to provide an improved arrangement for controlling the air flow through an induction system so as to permit smooth running and proper air fuel ratio, particularly during such conditions as blipping the throttle.
The use of fuel injection to provide more accurate control over the fuel air ratio, particularly on a cycle-to-cycle basis, is well-known. For a wide variety of reasons, injection into the induction system rather than directly into the combustion chamber may be more desirable. In addition to the problem previously noted, however, manifold injection causes a possibility of fuel being deposited on the walls of the intake passage. Although this fuel will eventually be distributed into the combustion chamber, the timing of the actual fuel introduction into the combustion chamber from the deposits on the intake passage wall is somewhat erratic and can cause uneven running.
The fuel that is deposited on the intake passage walls also is not swept away as rapidly as fuel deposited in other areas in the intake passage due to the laminar flow condition that exists on the peripheral surfaces of the intake passage.
It is, therefore, a still further object of this invention to provide an improved manifold arrangement system for an engine wherein any fuel that is deposited during the induction cycle is deposited in areas where the air flow will be greater and the fuel will be more likely to be swept into the combustion chamber on the cycle for which it was intended.
With engines embodying this technique of appropriately relating the induction system volume with the exhaust gas volume, it is substantially necessary to employ individual throttle valves for each intake port. This requires a complicated linkage system and in some applications, presents problems with placement of all of the components of the engine particularly with space that may be available.
It is, therefore, a still further object of this invention to provide an improved layout for the components of the engine and fuel injection system of a fuel-injected multi-cylinder internal combustion engine.
As an example of the components that are employed with a fuel injection system, generally the injection system for a multiple cylinder engine embodies a fuel rail that supplies fuel to a group of fuel injectors. In addition, it is generally the practice to control the pressure in the fuel supply system so that the fuel is supplied at the desired pressure ratio relative to the intake air with which it is mixed. This requires the use of pressure regulators and return conduits. In addition, the fuel supply system includes other components such as filters and the like. These components all take up space and in some instances, it is desirable to maintain the components as close to each other as possible so as to reduce pressure losses and the like.
It is, therefore, a still further object of this invention to provide an improved fuel supply system for a multiple cylinder fuel injected engine.
It is yet a further object of this invention to provide an improved combined fuel rail, pressure regulator and fuel filter arrangement for such engines.
In conjunction with the control systems for engine management including management of the fuel injection system, there are frequently employed sensors for sensing varying engine conditions. One sensor almost universally employed in the system is a throttle position sensor. This sensor senses the position of the throttle valve and thus provide an indication of load and/or operator demand for the control strategy.
Where the engine has plural throttle valves and at times this incorporates the use of plural throttle bodies, the positioning of the sensor can present significant difficulties, as is noted in the aforenoted co-pending application. In addition to the positional mounting problem, there is also the problem of transmitting the signal from the sensor to the control unit. This requires the use of wire transmitters and/or wire harnesses and can present some problem.
It is, therefore, a still further object of this invention to provide a more integrated throttle position sensor and control unit for engine management system.
In connection with the utilization of throttle position sensors, in order to obtain the high accuracy required for providing accurate signals, the sensor can become quite expensive. This can significantly add to the cost of the engine and even if accurate sensors are employed, the signals may not always be as accurate as desired.
It is, therefore, a still further object of this invention to provide an improved sensor and control arrangement wherein lower cost sensors can be utilized without sacrificing accuracy.
As has been noted, the use of these concepts with multiple cylinder engines frequently dictates the use of multiple throttle bodies for the engine. Although a single throttle body could be utilized for multiple cylinders, this presents certain problems in connection with alignment, attachment and accessibility. Therefore, frequently separate throttle bodies are employed. Where separate throttle bodies are employed, however, then movement or misalignment between the throttle bodies can cause binding in the throttle linkage and other problems.
It is, therefore, a still further object of this invention to provide an improved throttle body fuel injection system for a multiple cylinder engine wherein independent components can be utilized but wherein the components are attached in such a way to provide a rigid overall structure without having it be unitary in nature.